Hello, my name isXXXXX and I have over 20 years of experience as a veterinarian.
I am so sorry to hear that Reeses is in the palliative stages of Mast Cell tumor cancer and you are unable to get medication for him any longer.
I know that this is frustrating and painful for you to see him this way but you must understand all veterinarians licensed in the United States are bound by strict rules that each state enforces. If we do not follow those rules we can lose our license to practice and thus our ability to make a livelihood. We cannot write prescriptions for an animal we have never physically examined or haven't seen within a specific amount of time. That time varies from state to state but in most states it is within 6 months to one year.
I think you can understand that as much as we may empathize with a pet or owner we must protect ourselves too.
I can understand not wanting to put your fellow through the trauma of a car ride and the stresses of a veterinary clinic. How about having a mobile veterinarian come to him in the comfort of his own home? Here is a link to help you find one in your area:
There are some things that you can do for him in the meantime to help counter act the effects of a mast cell tumor and the histamines it releases.
1) Benadryl (diphenhydramine only don't use the combination products with decongestants and acetaminophen as they can be toxic to dogs) at 1mg to 2mg per pound or one 25mg capsule per 25 pounds of dog orally every 8 hours. Antihistamines block the systemic effects of the histamines a mast cell tumor releases.
2) Pepcid-ac (famotidine) at one 10mg tablet per 20 to 40 pounds of body weight
every 12 hours.
Prilosec (omeprazole) at one 10mg tablet per 20 to 40 pounds of body weight
every 24 hours.
These will reduce stomach acid, which tends to increase in response to the histamines released by the mast cells. They should reduce nausea and gastrointestinal ulceration formation.
I know that these over the counter medications aren't as helpful as prednisone would be, and they won't affect the primary size of the tumor, but they should decrease the side effects of the tumor for him and make him somewhat more comfortable.
Best of luck with your boy, I'm sorry that you and he are in this position.